I have 1.9:1 rockers, tog headers, cat delete, fwi, 180* stat, 3.3" pulley. I'm making about 8-9lbs of boost with no knock and was wondering how small of a pulley I could run with an IC? What hp gains would I be looking at?
Its a large invesment and I'm wondering if I should go this route or opt for a ported blower instead?

I don't know for sure, but I'd guess you could probably go another .2 smaller with your setup considering no KR, HOWEVER, that won't necessarily be true in a warmer climate. Woodburn might bite you.

Check over at CGP. A lot of I/C'ed cars are running sub 3.0 pulleys.

No 2 cars are alike but many intercooled L67s run 2.8" pullies on pump gas of 92 or 93 octane. You could expect around 11 to 12 lbs boost. What'* more, you could also run more ignition timing advance with an IC, in fact many will say you're better to go for more timing than boost so maybe a 3" pulley at 20* timing

You could expect significant power increases with the right supporting mods and proper tuning...somewhere around 30 horsepower.

Cheers,